Cracking foundations: How 2025’s summer drought is sinking UK homes

Ground shrinkage, more accurately known as subsidence, can be incredibly damaging to properties – so much so that the British Geological Survey (BGS) described this geological phenomenon on its website as being “one of the most damaging geohazards in Britain today, costing the economy an estimated £3bn over the past decade”.

Subsidence – and its sister process known as heave – occur predominantly in clay rich soils. Clay’s mineral properties allow it to hold large amounts of water – the changing volume of which relating to the drying or swelling of the soil can cause substantial ground movements.

When clay soils become wet, they can swell and lift structures, leading to heave. When clay soils dry, they can shrink and fracture, leading to subsidence.

In a 2021 report, the BGS estimated that while just 3% of UK homes were at risk of damage from subsidence in 1990, that number could grow to 11% by 2070.

Lee Jones, engineering geologist at the BGS, explained: “Of particular interest are areas with clay rich soils that shrink and swell with changes in moisture. For example, in the south east, many of the clay formations are too young to have been changed into stronger mud rocks, leaving them vulnerable to absorb and lose moisture.

“Dry weather and high temperatures are a major factor in the emergence of shrink-swell subsidence and looking to the future, increases in annual temperatures and variability in rainfall are very likely to continue.”

Clay type soils are typically found in the south east of England, including highly populated counties such as Kent, Surrey and Essex, putting a large number of homes at risk of property damage.

Figures from the Office for National Statistics published in July 2024 identified that the 2023 population of Kent was 1,610,300 people, for example.

Meanwhile, London – notably – is almost entirely located on a clay formation known as London clay.

Climate concerns

Given the connection between low rainfall and subsidence, changing climate dynamics are a concern for insurers looking to predict building damage and mitigate home or property claims.

In its latest Subsidence Risk Assessment report, published in May 2025, weather risk management firm EuroTempest predicted that this summer will see a growth in subsidence notifications, linking historical rainfall in the February to June period to a high numbers of claims.

This year’s February to June period has been the driest on record for the south east since 2000, the firm reported, as well as the seventh driest since its records began in 1836. Other notable dry years, such as 2003 and 2011, saw subsidence claims peak – although much of this volume depended on rainfall in the later summer months.

The firm explained: “Comparison years with similar year-to-date rainfall suggest that elevated claims numbers are highly likely following a dry spring and early summer. Above normal rainfall during July and August is possible and, under this scenario, it is possible that this year might see only slightly elevated claims numbers.

“However, considering the current long-range forecasts suggest a decreased chance of wet conditions through the next three months, a significant surge in claims due to subsidence is increasingly likely.”

Planning and prevention

Given the clear historical precedents, many insurance firms are trying to stay ahead of potentially high claims numbers that could arise this summer.

Stuart Thorniley, head of property growth at claims management company Innovation Group, told Insurance Times: “We’re already using smart automation behind the scenes to speed things up. Accurate and early diagnosis [of subsidence] is critical, but also key to this is making sure our people can still focus on what matters – customers.

“We’re also continuing to invest in innovation. This summer sees a wider rollout of our electrokinesis stabilisation (EKS) trials, led by technical director Richard Rollit and his team. This is a pioneering new technique that could transform how we stabilise properties in future, especially where tree removal isn’t an option. We’re hugely excited about the potential of this and hope it may have potential not just to treat subsidence, but to prevent it in the future.”

EKS uses electrical currents to stabilise clay soils, eliminating the need for excavation, underpinning, or tree removal – these latter methods have previously been the fixes employed by claims teams. EKS passes a low voltage electrical current through the soil, causing charged particles and water to migrate.

Thorniley also believes that a more comprehensive approach to managing subsidence may be needed in the future, one that integrates education, prevention and risk management.

He explained: “Looking ahead, we believe the industry has a shared responsibility to help homeowners understand what to expect during periods of high demand and really learn a bit more about subsidence – especially with the impact of global warming and more frequent heat waves meaning more properties may be at risk of subsidence.

“Solutions like EKS may one day have a preventive role, but for now, when we think of the bigger picture – as an industry, insurers, suppliers, the public, environmental groups and local authorities – we all need to work more closely together.

”It’s critical we find the right balance between protecting the environment and protecting people’s homes. There’s no simple answer, but by working together, we can find better, fairer solutions for everyone.”